Interpretive Summary: Two and three - dimensional analysis using close range digital photographs can be very useful in measuring changes in erosion on the landscape. Computer software exists for conducting photographic analysis but is often either cost prohibitive or very labor intensive to use. This paper describes a simple 2-D image-based technique used to conduct simple measurements photographically using software that would already typically be in use in an engineering office (i.e. computer aided design, image editing, and spreadsheet programs). The technique allows for the collection of a significant amount of supplemental information that can be analyzed in the office when time permits. The technique is very repeatable and results in reliable measurements when compared to actual physical measurements. This technique was demonstrated in this paper to be an effective safe method for measuring distances and locations on the landscape.

Technical Abstract:
Two and three - dimensional analysis using close range digital photographs can be very useful in measuring changes in erosion on the landscape. Computer software exists for conducting photographic analysis but is often either cost prohibitive or very labor intensive to use. This paper describes a simple 2-D image-based technique used to conduct simple measurements photographically using software that would already typically be in use in an engineering office (i.e. CAD, image editing, and spreadsheet programs). The technique allows for the collection of a significant amount of supplemental information that can be analyzed in the office when time allows. The technique is very repeatable and results in reliable measurements when compared to actual physical measurements. The accuracy of using these measurements was evaluated. The standard error was 17 mm with a coefficient of determination of 0.99 for the linear regression. The overall mean absolute deviation of residuals was 18 mm and the maximum absolute residual was 52 mm. The application selected for this paper is the documentation of headcut location and breach width opening during an embankment-overtopping test. This technique was demonstrated to be an effective method for measuring distances and locations on the landscape.